US Patent 7836675 Supercore sump vent pressure control

An active air pressure control apparatus for a bearing sump cavity in a gas turbine engine includes a bearing assembly supporting a rotatable shaft that connects a rotatable power turbine and a rotatable compressor. The active air pressure control apparatus also includes a sump cavity surrounding the bearing assembly, a sump pressurization cavity in flow communication with a source of pressurized air and in flow communication with the sump cavity, and a sump vent tube in flow communication with the sump cavity and an air/oil separator. The active air pressure control apparatus includes an adjustable valve in the sump vent tube, and a controllable blower in flow communication with the sump vent tube.